System and method for providing data-driven user authentication misuse detection

ABSTRACT

Systems, methods, and other embodiments are disclosed for data-driven user authentication misuse detection. In one embodiment, for a user authentication attempt to access a secure computer resource, user authentication log data having user attribute values is collected. The user authentication log data is transformed into a tracer data structure. The tracer data structure is augmented with timestamp data to generate an event data structure. It is determined whether the tracer data structure matches an existing tracer data structure stored in a rules database and, if not, a novelty flag is set to generate a new user behavior model filter. If the tracer data structure matches the existing tracer data structure: an existing user behavior model filter is applied, issuance of an alarm message or signal is controlled, and the existing user behavior model filter is updated based, at least in part, on the event data structure.

BACKGROUND

The security technologies and services market continues to grow asenterprises are challenged as never before in cyber space and investsignificantly in protecting their assets and their customers fromfraudulent activity. Conventional identity management (IdM) technologiesthat enterprises use to control user authentication and privileges arebecoming more vulnerable to misuse as users access corporate resourcesfrom a wider variety of devices, connection types, and geographicallocations.

Although enterprises may enforce strict use policies designed tominimize any chances of exposing user account credentials, humanfactors, technological weaknesses, and inevitable bugs in software andhardware components often allow attackers to obtain user accountcredentials and exploit them in fraudulent activities.

As an example, a phishing attack is one common attack scenario in whicha company's employees receive credible looking emails asking them toclick a certain link and perform a certain action requiring enteringtheir username and password. After obtaining a user's password, thefraudulent site may redirect the user to a valid company site, such thatthe user may not even realize that his/her account credentials have justbeen stolen.

The only line of defense of current IdM systems against phishing attacksis to couple with a spam detecting software that screens all inbound andoutbound emails and recognizes potential phishing emails. Unfortunatelysome phishing attacks disguise themselves so skillfully that they easilytrick general-purpose spam-filtering software into allowing such emailsas valid.

Another attack scenario example occurs when employees use weak andduplicate passwords for corporate systems and for other online services.Once attackers gain access to online services, which may have lowersecurity standards, they use the obtained account credentials to accesscorporate systems. It is almost impossible to detect such passwordbreaches with conventional IdM systems unless the attacker performsreadily noticeable, disruptive actions such as resetting the password orusing the compromised account in spamming or phishing campaigns.

Despite enterprises' use of sophisticated security solutions, includingfirewalls, anti-virus and anti-spyware suites, blacklists, spam filters,and so forth, there is a dangerously increasing number of attacksgetting through the traditional security measures. Additionally, thereare an increasing number of attacks due to the expanding range ofopportunities for attackers created by the emerging Internet of Things,the abundance of mobile and wearable devices, and the shift to cloudcomputing.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of the specification, illustrate various systems, methods, andother embodiments of the disclosure. It will be appreciated that theillustrated element boundaries (e.g., boxes, groups of boxes, or othershapes) in the figures represent one embodiment of the boundaries. Insome embodiments one element may be designed as multiple elements orthat multiple elements may be designed as one element. In someembodiments, an element shown as an internal component of anotherelement may be implemented as an external component and vice versa.Furthermore, elements may not be drawn to scale.

FIG. 1 illustrates one embodiment of a computer system, having acomputing device configured with misuse detection logic, providingdata-driven user authentication misuse detection;

FIG. 2 illustrates one embodiment of a method, which can be performed bythe misuse detection logic of the computer system of FIG. 1, to providedata-driven user authentication misuse detection;

FIG. 3 illustrates one embodiment of a user behavior model, which can beused in the misuse detection logic of the computer system of FIG. 1, todetect changes in a user's authentication behavior;

FIGS. 4 and 5 illustrate example embodiments of tables used in a rulesdatabase implementation of the computer system of FIG. 1; and

FIG. 6 illustrates one embodiment of a computing device upon which themisuse detection logic of a computing system may be implemented.

DETAILED DESCRIPTION

Computerized systems, methods, and other computerized embodiments aredisclosed that provide detection of malicious uses of user accounts. Inone embodiment, a system collects user authentication attempts data,transforms the data, augments the data with other data, autonomouslybuilds representations of account use patterns, and detects maliciousauthentication attempts. When used as part of multifactor authenticationprocess, the disclosed system allows the prevention of maliciousactivity. The system does not require any training (labeled) data orknowledge of the exact mechanisms used for user authentication misuse.The system is ready to use immediately after installation without theneed for an initial training data collection period.

The following terms are used herein with respect to various embodiments.

The term “authentication attempt”, as used herein refers to an effort bya person via a computer, or by the computer itself, to be approved toaccess a user account on another computer.

The term “authentication log message”, as used herein refers to acomputer message received by a computer, typically over a computernetwork, where the computer message was sent by a person via anothercomputer, or by the other computer itself, as part of an authenticationattempt.

The term “authentication log data”, as used herein refers to datacontained in an authentication log message.

The term “user attribute”, as used herein refers to a type ofauthentication log data associated with a characteristic of a userattempting to access a user account on a computer. Examples of userattributes include a user name, a client IP address, a resource name, alogin status, a timestamp, an authentication scheme, an authenticationpolicy, a partner, a failure code, a retry count, a session, and anauthentication level.

The term “user attribute value”, as used herein refers to a specificvalue (e.g., text, numerical, a combination of text and numerical) thata user attribute is assigned or takes on.

The term “account usage pattern”, as used herein refers to a recordedrepresentation (e.g., a computerized filter or model) of valid(non-malicious) attempts and malicious attempts by a user toauthenticate to a user account on a computer.

Overview

In one embodiment, a method makes it possible to reliably detectmalicious attempts to access a user account on a computer system,without using training (labeled) data, by identifying impossiblecorrelations in user authentication behavior. The method is based onfirst detecting an impossible condition that is not realizable underexpected account usage scenarios. Upon, detection of such a condition,rule-based reasoning, called filtering, is used to analyze theimpossible condition and either resolve it as normal or flag it assuspicious. The system attempts to rationally explain the impossibleevent to minimize false alarms, which minimizes use of system andsecurity personnel resources by only responding to infrequent events,thus allowing scaling to hundreds of thousands of users.

In one embodiment, tracking user behavior without labeling is achieved.Although not required, specific user behavior can be identified assuspicious and automatically cause an alarm whenever the suspiciousbehavior is observed, where the identification can happen in real time.

In one embodiment, data representation of user authentication events by“tracers” that compactly represent the user actions and times isaccomplished. If a tracer has appeared before, only the new event timeis saved instead of a new tracer. This enables correlation and discoveryof patterns of activations of tracers (rule firing times or timestamps).Filters and alarms can be based on tracers for a single user or multipleusers.

In one embodiment, the ability to detect malicious use of userauthentication data even when the authentications are successful isprovided. By observing user authentication behavior over time, thesystem builds a comprehensive model of each user's behavior. Even if anattacker has the user's ID and password and is able to successfullyauthenticate, the attacker cannot replicate the user behavior, whichwill lead to deviations from the model.

In this manner, malicious attempts to access an account of a user on acomputer can be detected and thwarted.

DETAILED DESCRIPTION WITH RESPECT TO THE DRAWINGS

FIG. 1 illustrates one embodiment of a computer system 100, having acomputing device 105 configured with misuse detection logic 110,providing data-driven user authentication misuse detection. In oneembodiment, misuse detection logic 110 may be part of a larger computerapplication (e.g., a computerized security application), configured toprevent malicious and unauthorized access to user accounts.

In one embodiment, the system 100 is a computing/data processing systemincluding an application or collection of distributed applications forenterprise organizations. The applications and computing system 100 maybe configured to operate with or be implemented as a cloud-basednetworking system, a Software as a Service (SaaS) architecture, or othertype of computing solution.

With reference to FIG. 1, in one embodiment, misuse detectionlogic/module 110 is implemented on the computing device 105 and includeslogics or modules for implementing and controlling various functionalaspects of misuse detection logic/module 110. In one embodiment, misusedetection logic/module 110 includes visual user interface logic/module120, message parsing logic/module 130, tracer matching logic/module 140,impossible event logic/module 150, filter logic/module 160, and explainlogic/module 170.

Other embodiments may provide different logics or combinations of logicsthat provide the same or similar functionality, and control of thatfunctionality, as misuse detection logic 110 of FIG. 1. In oneembodiment, misuse detection logic 110 is an executable applicationincluding algorithms and/or program modules configured to perform thefunctions of the logics. The application is stored in a non-transitorycomputer storage medium. That is, in one embodiment, the logics ofmisuse detection logic 110 are implemented as modules of instructionsstored on a computer-readable medium.

The computer system 100 also includes a display screen 180 operablyconnected to the computing device 105. In accordance with oneembodiment, the display screen 180 is implemented to display views ofand facilitate user interaction with a graphical user interface (GUI)generated by visual user interface logic 120. The graphical userinterface may be used, for example, for controlling user specificationof filter parameters associated with filters (e.g., a user behaviormodel filter) of filter logic 160, as discussed later herein. Thegraphical user interface may be associated with a misuse detectionalgorithm and visual user interface logic 120 may be configured togenerate the graphical user interface.

In one embodiment, the computer system 100 is a centralized server-sideapplication that provides at least the functions disclosed herein andthat is accessed by many users via computing devices/terminalscommunicating with the computer system 100 (functioning as the server)over a computer network. Thus the display screen 180 may representmultiple computing devices/terminals that allow users (e.g., accountusers) to access and receive services from misuse detection logic 110via networked computer communications.

In one embodiment, the computer system 100 further includes a rulesdatabase device 190 operably connected to the computing device 105and/or a network interface to access the rules database device 190 via anetwork connection. In accordance with one embodiment, the rulesdatabase device 190 is configured to store tracer data structures havinguser authentication attributes organized in a common format. The commonformat includes user attribute values paired with a corresponding userattribute type.

Referring back to the logics of misuse detection logic 110 of FIG. 1, inone embodiment, visual user interface logic 120 is configured togenerate a graphical user interface (GUI) to facilitate user interactionwith misuse detection logic 110. For example, visual user interfacelogic 120 includes program code that generates and causes the graphicaluser interface to be displayed based on an implemented graphical designof the interface. In response to user actions and selections via theGUI, associated aspects of misuse detection logic 110 may bemanipulated.

Referring again to FIG. 1, in one embodiment, the rules database device190 is configured to store tracer data structures having user attributesvalues in a common format. In one embodiment, user authentication logdata from an authentication log message of an authentication attempt istransformed into a tracer data structure. The tracer data structureincludes multiple user attribute values (parsed from the authenticationlog data). Each user attribute value is paired with a correspondingattribute type (i.e., in the common format). A user attribute value maycorrespond to a user name value, a client IP address value, a resourcename value, a login status value, a timestamp value, an authenticationscheme value, an authentication policy value, a partner value, a failurecode value, a retry count value, a session value, and an authenticationlevel value. Other types of user attribute values are possible as well,in accordance with other embodiments.

As users attempt to authenticate to various resources, the details ofauthentications are being logged and analyzed by the system 100 toidentify misuse of user accounts (e.g., exploitation by external hackersor malicious insiders). In one embodiment, message parsing logic 130 isconfigured to receive authentication log messages from users attemptingto authenticate to the computer system 100 to, for example, access auser account. The authentication log messages come from other computers,for example, via network communications (e.g., via the internet).

For each authentication attempt (i.e., for each authentication logmessage received), user authentication log data is collected by messageparsing logic 130 from the authentication log message. User attributevalues are parsed from the user authentication log data by messageparsing logic 130 such that the user authentication log data istransformed into a tracer data structure having the user attributevalues. The tracer data structure is organized in the common formatwhere each of the user attribute values is paired with a correspondingattribute type.

For example, let U={u} denote the set of users. The users u ∈ U arecharacterized by a finite number of attributes a₁, a₂, . . . , a_(k).Each attribute a takes values from some finite domain D_(i)=v₁ ^(i), v₂^(i), . . . , v_(pi) ^(i)}. For example, a₁ can be “client IP” and takevalues from D₁={10.141.208.37, 10.141.208.38, 10.141.208.43}, a₂ can be“resource name” with values from D₂={mailapp, orgchartapp, salesapp},and a₃ can be “status” with values from D₃={success, fail}.

A tracer is a data structure composed of a number of attribute-valuepairs. A tracer may include all k attributes or any subset of them. Thefollowing notation is used for a tracer:T=[a₁=v_(j) ¹:a₂=v₁ ²:a₃=v_(s) ³],

and has the following interpretation: attribute value v_(j) ¹ isobserved for attribute type a₁, value v_(l) ² is observed for attributetype a₂, and value v_(s) ³ is observed for attribute type a₃. Messageparsing logic 130 parses the received authentication log message andcreates a tracer data structure T representing the log message.

In one embodiment, for each authentication attempt (i.e., for eachauthentication log message received), tracer matching logic 140 isconfigured to attempt to match the tracer data structure to an existingtracer data structure stored in the rules database device 190. Anorganization of the rules database structure is discussed later hereinwith respect to FIG. 4 and FIG. 5.

When a matching tracer data structure is found in the rules databasedevice 190, tracer matching logic 140 is configured to update a list oftimestamps (firing times) associated with the tracer data structure inthe rules database device 190 with a new timestamp (a new firing time).Timestamp data represents a time at which the user authentication logdata is observed by the computer system 100 (e.g., observed by messageparsing logic 130).

When a matching tracer data structure is not found in the rules databasedevice 190, tracer matching logic 140 is configured to create and storea new tracer data structure in the rules database device 190. Tracermatching logic 140 is also configured to set a novelty flag associatedwith the new tracer data structure, and set a first timestamp in a listof timestamps associated with the new tracer data structure, inaccordance with one embodiment.

In one embodiment, tracer matching logic 140 is also configured togenerate an event data structure by augmenting the tracer data structurewith timestamp data. Again, timestamp data represents a time at whichthe user authentication log data is observed by the computer system 100(e.g., observed by message parsing logic 130). An event data structure Eincludes a tracer T and a timestamp t such that E={T, t}. The event datastructure E indicates that the values of attributes specified by tracerT have been observed at time t.

A user (whether valid or malicious) may attempt to authenticate to thecomputer system many (e.g., one hundred) times in a row, resulting in asequenced stream of event data structures E₁, E₂, . . . , E_(t) beinggenerated by and output from tracer matching logic 140. In oneembodiment, impossible event logic 150 is configured to receive thesequenced stream of event data structures E₁, E₂, . . . , E_(t) fromtracer matching logic 140 and detect an impossible event pattern withinthe authentication log messages by analyzing the sequenced stream ofevent data structures E₁, E₂, . . . , E_(t) for the multipleauthentication attempts.

In accordance with one embodiment, the impossible event pattern is ahypersonic travel pattern. The hypersonic travel pattern describes asituation in which the speed of travel of a user to physicallyauthenticate from distant geographical locations is greater than thespeed of sound traveling in air. Based on IP addresses used in twoconsecutive authentication events, the geographical location of the useris determined. The geographical location is then converted into latitudeand longitude values.

The distance between two locations is computed using the great-circledistance or the Vincenty formula applied to a sphere. When a hypersonicpattern is detected (i.e., the time between two consecutiveauthentication events is less than the time required to travel thedistance between the two locations at the speed of sound), impossibleevent logic 150 flags the event as being impossible. In one embodiment,impossible event logic 150 sends an impossible event flag to explainlogic 170. The detection of other types of impossible events may bepossible as well, in accordance with other embodiments.

In one embodiment, filter logic 160 is configured to receive thesequenced stream of event data structures E₁, E₂, . . . , E_(t) fromtracer matching logic 140. Filter logic 160 is also configured to detecta change in behavior of a user by applying a user behavior model filter,representing account usage patterns of the user, to the sequenced streamof event data structures E₁, E₂, . . . , E_(t) for the multipleauthentication attempts. An example embodiment of a user behavior modelfilter is discussed herein with respect to FIG. 3. Explain logic 170 isconfigured to engage filter logic 160 in an attempt to explainimpossible events detected by impossible event logic 150, in accordancewith one embodiment, as discussed later herein.

Filter logic 160 may also (or alternatively) employ other types offilters for the purpose of being engaged by explain logic 170 to explainobserved impossible events in a sequenced stream of event datastructures. For example, in one embodiment, filter logic 160 includes anovelty filter or novelty detector. When a user has never used aspecific IP to access a specific resource, the novelty filter isconfigured to mark the IP as novel, or mark the combination of IP andresource as novel when the IP itself is not novel but was used for thefirst time to authenticate to the given resource. In one embodiment, thenovelty filter can be denoted as B_(novelty)(F_(t)) with values from{new, used}, where F_(t) corresponds to a feature associated with usercharacteristics.

In another embodiment, filter logic 160 includes a blacklist filter. Ablacklist filter may be associated with a certain attribute orattributes. For example a blacklist of IPs can be used to determine ifthe current IP is a known malicious IP or an IP noticed in previousmalicious activities, or an IP from a high risk network block. In oneembodiment, a blacklist filter can be denoted as B_(blacklist)(F_(t))with values from {listed, notlisted}.

In another embodiment, filter logic 160 includes a pattern filter for acustomer support activity. For example, determining if other IPs fromthe same network block were used by the user to access specificresources could indicate normal activity. In one embodiment, a patternfilter can be denoted as B_(support)(F_(t)).

Other types of filters may be employed by filter logic 160, inaccordance with other embodiments, and serve as examples which do notlimit the variety of filters that can be used for explaining impossibleevents. In some embodiments, filters may be configured in filter logic160 with respect to determining the following:

-   -   Incomplete geographical location of the IP    -   IP-based location change within same country    -   Company owned IP to company owned IP    -   Company private IP to company private IP    -   Company VPN IP to company VPN IP    -   User behavior change or/and anomaly    -   IPs previously used by user    -   IPs in user's country of residence    -   IPs from whitelists    -   IPs from blacklists    -   Customer support-like patterns meaning normal activity

Again, in accordance with one embodiment, explain logic 170 isconfigured to engage filter logic 160 in an attempt to explainimpossible events detected by impossible event logic 150. Explain logic170 is configured to engage filter logic 160 to determine a validexplanation for the impossible event pattern detected by impossibleevent logic 150, and generate a corresponding valid explanation message.When a valid explanation cannot be determined by explain logic 170,explain logic 170 is configured to generate an alarm message or signalindicating a malicious authentication attempt. Therefore, when animpossible event pattern is detected by impossible event logic 150, theexplain logic is engaged. When the impossible event pattern passes anappropriate set of filters of filter logic 160, which could be any orall of the filters, the pattern is explained, and the event is notflagged. When the pattern cannot be explained, the event is flagged, andan alarm is sent (e.g., transmitted via network communications) to, forexample, a third party computer.

Explain logic 170 implements the conditions and interoperability ofvarious filters and may include logical and functional operations andvarious combinations of those. A flagged event may be sent for furtheranalysis, in accordance with one embodiment. In a variation embodiment,a group of security personnel may take further action to investigate theincident. In still another variation embodiment, a flagged event can bereported through an existing security information and event management(SIEM) system. In yet another variation embodiment, multifactorauthentication may be automatically employed.

In another variation embodiment, the flagged event can be furtheranalyzed and can be confirmed or cleared. If the event is confirmed, thecorresponding user behavior states may be labeled as compromised. If theuser transitions from an unlabeled state to a compromised state, a flagcan be raised immediately regardless of the presence or absence of animpossible event pattern.

In this manner, misuse detection logic 110 of the computer system 100 ofFIG. 1 provides a data-driven approach to user authentication misusedetection. As users attempt to authenticate to various resources, thedetails of authentication attempts are being logged and analyzed by thesystem 100 to identify misuse of user accounts (e.g., exploitation byexternal hackers or malicious insiders). The system 100 processes astream of features by detecting impossible events, applying filters toexplain the observed impossible events, and alarming on impossibleevents that could not be rationally explained. One of the filters can bea user behavioral change and anomaly detection filter (see FIG. 3), forexample. The system 100 can be used as a stand-alone securityapplication that flags suspicious accounts for an in-depthinvestigation, and can also be used as a trigger for multi-factorauthentication or other preventive measures.

FIG. 2 illustrates one embodiment of a method 200, which can beperformed by misuse detection logic 110 of the computer system 100 ofFIG. 1, to provide data-driven user authentication misuse detection.Method 200 describes operations of misuse detection logic 110 and isimplemented to be performed by misuse detection logic 110 of FIG. 1, orby a computing device configured with an algorithm of the method 200.For example, in one embodiment, method 200 is implemented by a computingdevice 105 configured to execute a computer application. The computerapplication is configured to process data in electronic form andincludes stored executable instructions that perform the functions ofmethod 200.

Method 200 will be described from the perspective that users attempt tologin to the computer system 100 of FIG. 1 to be authenticated to accessuser accounts. Some attempts are illegitimate or malicious and method200 acts to detect such attempts. Method 200 does not require anytraining (labeled) data or knowledge of exact mechanisms used for userauthentication misuse. Referring to FIG. 1 and FIG. 2, for each ofrecent multiple user authentication attempts to the computing device 105by a user via user authentication log messages, user authentication logdata having user attribute values is collected from the log messages atblock 202. In accordance with one embodiment, message parsing logic 130of FIG. 1 is configured to receive and collect the user authenticationlog data.

Also, for each of the recent multiple user authentication attempts, theuser authentication log data is transformed into a tracer data structurehaving the user attribute values organized in a common format at block204. The common format of the tracer data structure includes each of theattribute values paired with a corresponding attribute type. Inaccordance with one embodiment, the user authentication log data istransformed by message parsing logic 130 of FIG. 1, at least in part, byparsing the user authentication log data into the user attribute valuesand pairing each attribute value with a corresponding attribute type.

Furthermore, for each of the multiple user authentication attempts, anattempt is made to match the tracer data structure with an existingtracer data structure stored in the rules database device 190 at blocks206 and 208. When a match occurs, a list of timestamps for the existingtracer data structure is updated with a new timestamp. The list oftimestamps represents firing times (as data) at which the userauthentication log data is observed by the computing device 105. When amatch does not occur, the tracer data structure is stored as a newtracer data structure in the rules database device 190 and a noveltyflag and a first timestamp associated with the new tracer data structureare set. In accordance with one embodiment, tracer matching is performedby tracer matching logic 140 of FIG. 1.

Whether or not a match occurs, for each of the recent multiple userauthentication attempts, the tracer data structure is augmented with thecorresponding timestamp data to generate an event data structure atblocks 210 and 212, representing a recent event. Again, the timestampdata represents a firing time at which the user authentication log datais observed by the computing device 105 (e.g., by message parsing logic130). In accordance with one embodiment, an event data structure isgenerated by tracer matching logic 140 of FIG. 1.

Once the event data structures representing the recent authenticationattempts are generated at blocks 210 and 212, the event data structuresare analyzed by a first filter at block 215 representing a user behaviormodel (see filter 300 FIG. 3). The first filter at block 215 representsaccount usage patterns of a user and, in accordance with one embodiment,is implemented as part of filter logic 160 in FIG. 1. One embodiment 300of the first filter at block 215 is discussed in detail herein withrespect to FIG. 3.

In accordance with one embodiment, the user behavior model of the firstfilter at block 215 may be initially generated by transforming anoriginal set of event data structures, derived from an original set ofauthentication attempts by the user, into features that describeauthentication behavior characteristics of the user (see FIG. 3). Theuser behavior model may be initially generated without having to trainthe user behavior model using truth-labeled training data, and withouthaving apriori knowledge of user authentication misuse.

Upon receiving the event data structures from block 212 corresponding tothe recent authentication attempts, the first filter at block 215 may beupdated based on the analysis of the event data structures to update theaccounts usage patterns of the user as reflected in the event datastructures. Also, the first filter at block 215 may be used to analyzethe event data structures to determine whether the recent authenticationattempts represent a deviation from expected account usage patterns ofthe user (i.e., to detect an anomaly).

Other filters may be provided as well (e.g., a second filter at block216 and a third filter at block 218) which are configured to analyze theevent data structures from block 212. Such other filters may includeembodiments of the filters discussed previously herein with respect toFIG. 1, including a novelty filter and a blacklist filter, for example.In accordance with one embodiment, user specification of filterparameters and thresholds associated with the filters may be providedvia a graphical user interface or an application program interface.

In addition to being analyzed by the filters at blocks 215, 216, and218, in the method 200, the event data structures representing theauthentication attempts that are generated at blocks 210 and 212 arealso analyzed at blocks 214 and 220 to determine if an impossible eventpattern exists within the authentication log messages. In accordancewith one embodiment, the impossible event pattern is a hypersonic travelpattern. As discussed previously herein with respect to FIG. 1, ahypersonic travel pattern indicates that a speed of travel of a user(e.g., a malicious user), to physically authenticate from distantgeographical locations, is greater than the speed of sound through air.Other impossible event patterns are possible as well, in accordance withother embodiments. In one embodiment, impossible event logic 150 of FIG.1 is configured to detect an impossible event pattern in a sequence ofevent data structures.

When an impossible event pattern is not detected, the method 200proceeds to block 222, where the method continues to monitor and analyzereceived authentication log messages as previously described herein.When an impossible event pattern is detected (e.g., a hypersonic travelpattern), the method 200 proceeds to block 224 and attempts to explainthe impossible event pattern.

An impossible event pattern may be explained at block 224 by engagingone or more of the filters, for example, at blocks 215, 216, and 218.Attempts to explain a detected impossible event pattern have beenpreviously discussed herein with respect to FIG. 1. For example, in oneembodiment, explain logic 170 of FIG. 1 engages filter logic 160 of FIG.1 when impossible event logic 150 of FIG. 1 detects an impossible eventpattern.

At block 226, when an impossible event pattern has been explained atblock 224, then the method 200 proceeds from block 226 to block 230where the method continues to monitor and analyze receivedauthentication log messages as previously described herein. However,when an impossible event pattern cannot be explained at block 224, thenthe method 200 proceeds from block 226 to block 228 and generates analarm message or signal. The alarm message or signal indicates that amalicious authentication attempt may have been detected and that furtherinvestigation is warranted.

In this manner, the method 200 of FIG. 2 may be implemented on misusedetection logic 110 of the computer system 100 of FIG. 1 to detectinstances of misuse by authorized or unauthorized users, in accordancewith one embodiment. The method 200 is able to accommodateauthentication attempts by many users and reliably detect maliciousauthentication attempts, providing a low false alarm rate.

FIG. 3 illustrates one embodiment of a user behavior model filter 300(e.g., a user behavioral change and anomaly detection filter) which canbe used in the misuse detection logic 110 of the computer system 100 ofFIG. 1 to detect changes in a user's authentication behavior. In oneembodiment, the user behavior model filter 300 is implemented at block215 of the method 200 of FIG. 2.

In one embodiment, original authentication events Et are transformedinto features (at block 302) that describe various characteristics of auser's authentication behavior. The feature transformation produces afeature stream F₁, F₂, . . . , F_(t), where each feature F_(t) is am-vector with values in R^(m), F_(t)=(f_(1t), f_(2t), . . . , f_(mt)).Each feature can be computed based on a single event or based on a groupof events.

For example, one of the features corresponds to a login success ratewhich is the fraction of login attempts that were successful (orsuccessful from the first attempt). Such a feature would have a singlevalue (m=1). Another feature can be the association strength amongvarious attributes or same attribute (auto-association). For example, astrong association among “client IP” and “resource name” can indicate anexisting user's preference to access certain resources from certaindevices or locations. Such a feature is an m-vector with m equal to thenumber of all 2-way, 3-way, . . . , k-way associations. Each userpossesses a specific set of values for such features. By observingfeatures over time, the system builds a comprehensive model of userauthentication behavior.

In one embodiment, the strength of association among differentattributes is used as the behavioral features. Such a choice ismotivated by the fact that association among attributes uniquelycharacterizes a specific user. Even if an attacker knows a user'scredentials and resources to access, they have no knowledge of theuser's habits of accessing certain resources from certain IPs and atcertain times or in a certain sequence. For this, the attacker needsaccess to the user's authentication history, which is impossible for anattacker to obtain in most situations.

More precisely, given k attributes a₁, a₂, . . . , a_(k) there are

$\begin{pmatrix}k \\2\end{pmatrix}\quad$two-way associations,

$\begin{pmatrix}k \\3\end{pmatrix}\quad$tnree-way associations, etc. For k=3 the feature vector is 4-dimensionalwith three (3) two-way associations and one (1) three-way association:F_(t)=[A_(t)(a₁, a₂), A_(t)(a₁, a₃), A_(t)(a₂, a₃), A_(t)(a₁, a₂, a₃)].If the number of attributes is large, the number of possibleassociations is very large. A feature selection method can be used toselect only strong associations for the feature vector. In oneembodiment, the low rank associations such as two-way and three-way areused because the low rank associations are strong. High rankassociations, such as, for example, ten-way associations, are weak andare less reliable for behavior modeling. However, if there is credibleprior information about a discriminative significance of a specificmulti-way association, it may also be used in the feature vector.

Associations are computed using a sliding window of variable length intime but fixed size in number of events. The length of the window equalsthe number of events sufficient for the associations to be statisticallysignificant if they exist. Specifically, in one embodiment, the windowsize is selected to be:

W=min(N), such that M_(s){N, k}≤0.01,

where M_(s){N, k}=λ[(λ−1)/λ]^(N) and λ=Π_(i=1) ^(k)|Di|, where k is thenumber of attributes, and D_(i) is the value domain of attribute a_(i).

Association is computed as the ratio of the unique combinations ofattributes observed in the window divided by the number of all possibleattributes combinations.

${A_{t}\left( {a_{i},a_{j}} \right)} = {1 - \frac{{{Wt}\left\lbrack {{observed}\mspace{14mu}{combinations}} \right\rbrack}}{\;{{all}\mspace{14mu}{possible}\mspace{14mu}{combinations}\mspace{14mu}{of}\mspace{14mu}{values}\mspace{14mu}{ai}\mspace{14mu}{and}\mspace{14mu}{aj}}\; }}$

If the user uses (e.g.) ten (10) different IPs to access ten (10)different resources, and in a time window it is observed that the userused every IP to access every resource, then there is obviously noassociation between these two attributes, A_(t)(a_(i), a_(j))=0 (i.e.,it is impossible to conclude that if a user uses a specific IP then theuser most likely is going to access a specific resource). However, ifthe user uses certain IPs to access certain resources (e.g., accessingcertain applications from home and other applications from the office),then there is an existing association, A_(t)(a_(i), a_(j))>0, thatreflects the user's preference or habit to access certain resources fromcertain IPs or devices or locations. The set of associations and theirinterplay is a unique fingerprint of a user's authentication behavior,which is impossible to reproduce intentionally by an attacker withoutdetailed knowledge of the user's historical authentication behavior.

In a variation, the association strength can be computed as the ratio ofthe number of the combinations observed in the window divided by thenumber of possible combinations of values observed in the window.

${{A_{t}\left( {a_{i},a_{j}} \right)} = {1 - \frac{{{Wt}\left\lbrack {{observed}\mspace{14mu}{combinations}} \right\rbrack}}{{{{Wt}\lbrack{Di}\rbrack}}{{{Wt}\lbrack{Dj}\rbrack}}}}},$

where “W_(t)[D_(i)] subset D_(i)” denotes a subset of values from D_(i)observed in the given window W_(t)=(E_(t), E_(t−1), . . . , E_(t−w)) and|W_(t)[D_(i)]| is the number of elements in the subset.

Such a variant of association strength addresses the problem that mayarise from a large number of possible values of a certain attribute suchas client IP and the fact that over time a user may use a certain subsetof values and then never use it again. This problem arises due to thenature of attributes such as dynamic and mobile assigned IPs for whichthe subset of IPs may change completely over time without a change inuser behavior.

There are other ways to compute association strength using weighting,smoothing, or other techniques, in accordance with other embodiments.There are other features that may possess similar desirable propertiesto represent individual user characteristics impossible to reproduceintentionally by an attacker, in accordance with other embodiments.

The system further determines if the current feature vector F_(t) isanomalous compared to the previous values of the features based onclustering (at blocks 306 to 332). In one embodiment, clusteringtechniques (e.g., tri-point data clustering techniques referred to asTPC herein) found in U.S. Pat. No. 9,147,167 and U.S. published patentapplication US20140280146 may be used (at blocks 318 to 324). U.S. Pat.No. 9,147,167 and U.S. published patent application US20140280146 areboth incorporated herein by reference in their entirety.

The clustering techniques found in U.S. Pat. No. 9,147,167 and U.S.published patent application US2014028014 have the advantage ofdetermining the number of clusters automatically. All features untiltime t are clustered by TPC to produce clusters denoted as C₁, C₂, C₃,etc, (at blocks 310 to 316). The current feature vector F_(t) (at block304) is tested against these clusters (at blocks 318 to 332). If Ftbelongs to one of the clusters C(F_(n))=C_(z) and F_(t−1) belongs to thesame cluster, then no change in behavior is detected (at blocks 338,340, 342, and 346). If F_(t) belongs to one of the clusters C_(z), andF_(t−1) is not ∈ C_(z) (i.e., F_(t) and F_(t−1) belong to differentclusters), then a transition or change in behavior is detected (at block338, 340, 342, and 344). Notice that in one embodiment, z=s, wheres=argmax_(i) TPC(C_(i), F_(t)) (at block 440) and TPC is the similaritycomputed as described in U.S. Pat. No. 9,147,167 and U.S. publishedpatent application US20140280146. In a variation, z can be any clusterfor which the similarity TPC(C_(z), F_(t))>0 is positive. If F_(t) doesnot belong to any clusters, then an anomaly is detected (at blocks 334and 336).

Notice that many clustering techniques assign a cluster to any datapoint (a feature vector in this application). For example, k-meansclustering will assign a cluster to any point. The point will beassigned to the cluster with the closest center so that an additionaltest is required to determine if the point is sufficiently far from allthe cluster centers to be anomalous. The distance from the clustercenters is another configurable user parameter.

TPC performs cluster assignment by evaluating the similarity of the datapoint to each cluster. If the point is not similar to any of theclusters, it is an anomaly. If the point is similar to several clusters,the data point is assigned to the cluster with the highest similarity.The advantage of this approach compared to the prior art is thattraining data is not needed and user behavior does not need to belabeled as normal or anomalous. The behavior change and anomaly isprovided as a service without the need for training data with behaviorlabeled as normal or anomalous as required by the prior art.

Because it is impossible to label a detected user anomaly as a maliciousattempt or a legitimate change in user behavior without feedback fromadditional challenges, approaches based on training from known maliciousbehavior are impractical due to the limited number of known anomaliesthat can be identified and will miss previously unseen security threats.The disclosed method herein detects both previously seen and unseensecurity threats as it is not based on learning previously knownpatterns of normal or anomalous behavior.

In this manner, a user behavior model filter can be generated and usedto detect changes in a user's authentication behavior in a vicinity ofthe events of interest.

FIGS. 4 and 5 illustrate example embodiments of tables used in a rulesdatabase implementation of the rules database device 190 of the computersystem 100 of FIG. 1. Table 410 is a models table that is configured tokeep track of multiple models than can co-exist in the rules database(e.g., different versions of models, or models covering different timeranges, or models customized for specific user groups or use cases,including some demo models).

Table 420 is a users table that is configured to maintain user types andemails. User types may include internal, external, partner, customer,etc. Table 430 is a rulesets table that is configured to relate aruleset to a model via model_id and to a user via user_id. Table 430also maintains the number of cascades in the ruleset as well as thecreation and update times. Rule-rank specifies the rank of rules (i.e.,the number of domains in the rules).

Table 440 is a rules table that is configured to contain rules. Eachrule is associated with a model (ruleset) and a user and a cascade ofthe ruleset. Table 450 is a fired table that is configured to keep trackof firing times (timestamps) of every rule for further correlation ofrule firing times. Table 450 relates time_fired to a unique rule viarule_id and to a unique ruleset via ruleset_id.

Table 460 is an attribute type table that is configured to containadmissible attribute types such that attribute values can beinterpreted. Table 510 is an attributes table that is configured tomaintain the list of attributes used in the rules. Table 520 is anattribute values table that is configured to contain admissible valuesfor each attribute. Table 530 is a domains table that is configured tocontain domain rules. Table 530 describes each domain by an attribute_idand a value_id and maintains precision value of the domain indom_precision. Table 530 also relates the domain to a unique rule viarule_id and to a unique ruleset via ruleset_id.

Computing Device Embodiment

FIG. 6 illustrates an example computing device that is configured and/orprogrammed with one or more of the example systems and methods describedherein, and/or equivalents. FIG. 6 illustrates one embodiment of acomputing device upon which misuse detection logic of a computing systemmay be implemented. The example computing device may be a computer 600that includes a processor 602 and a memory 604 operably connected by abus 608.

In one example, the computer 600 may include misuse detection logic 630(corresponding to misuse detection logic 110 from FIG. 1) which isconfigured to provide data-driven user authentication misuse detection.In different examples, logic 630 may be implemented in hardware, anon-transitory computer-readable medium with stored instructions,firmware, and/or combinations thereof. While the logic 630 isillustrated as a hardware component attached to the bus 608, it is to beappreciated that in other embodiments, logic 630 could be implemented inthe processor 602, a module stored in memory 604, or a module stored indisk 606.

In one embodiment, logic 630 or the computer 600 is a means (e.g.,structure: hardware, non-transitory computer-readable medium, firmware)for performing the actions described. In some embodiments, the computingdevice may be a server operating in a cloud computing system, a serverconfigured in a Software as a Service (SaaS) architecture, a smartphone, laptop, tablet computing device, and so on.

The means may be implemented, for example, as an ASIC programmed tofacilitate the performing of data-driven user authentication misusedetection. The means may also be implemented as stored computerexecutable instructions that are presented to computer 600 as data 616that are temporarily stored in memory 604 and then executed by processor602.

Logic 630 may also provide means (e.g., hardware, non-transitorycomputer-readable medium that stores executable instructions, firmware)to generate a user behavior model filter, representing account usagepatterns of a user, based on an event data structure for each ofmultiple user authentication attempts to the computing device.

Generally describing an example configuration of the computer 600, theprocessor 602 may be a variety of various processors including dualmicroprocessor and other multi-processor architectures. A memory 604 mayinclude volatile memory and/or non-volatile memory. Non-volatile memorymay include, for example, ROM, PROM, and so on. Volatile memory mayinclude, for example, RAM, SRAM, DRAM, and so on.

A storage disk 606 may be operably connected to the computer 600 via,for example, an input/output interface (e.g., card, device) 618 and aninput/output port 610. The disk 606 may be, for example, a magnetic diskdrive, a solid state disk drive, a floppy disk drive, a tape drive, aZip drive, a flash memory card, a memory stick, and so on. Furthermore,the disk 606 may be a CD-ROM drive, a CD-R drive, a CD-RW drive, a DVDROM, and so on. The memory 604 can store a process 614 and/or a data616, for example. The disk 606 and/or the memory 604 can store anoperating system that controls and allocates resources of the computer600.

The computer 600 may interact with input/output devices via the i/ointerfaces 618 and the input/output ports 610. Input/output devices maybe, for example, a keyboard, a microphone, a pointing and selectiondevice, cameras, video cards, displays, the disk 606, the networkdevices 620, and so on. The input/output ports 610 may include, forexample, serial ports, parallel ports, and USB ports.

The computer 600 can operate in a network environment and thus may beconnected to the network devices 620 via the i/o interfaces 618, and/orthe i/o ports 610. Through the network devices 620, the computer 600 mayinteract with a network. Through the network, the computer 600 may belogically connected to remote computers. Networks with which thecomputer 600 may interact include, but are not limited to, a LAN, a WAN,and other networks.

Systems, methods, and other embodiments have been described that areconfigured to provide data-driven user authentication misuse detection.In one embodiment, a computer system having a processor and a rulesdatabase device are provided. The rules database device is configured tostore tracer data structures having user authentication attributesorganized in a common format. The computer system includes messageparsing logic configured to, for each of multiple authenticationattempts to the computer system via authentication log messages, collectuser authentication log data having user attribute values. Messageparsing logic is also configured to, for each of the multipleauthentication attempts, transform the user authentication log data intoa tracer data structure having the user attribute values in the commonformat at least in part by parsing the user authentication log data intothe user attribute values. The computer system also includes tracermatching logic configured to, for each of the multiple authenticationattempts, attempt to match the tracer data structure to an existingtracer data structure stored in the rules database device. Tracermatching logic is also configured to, for each of the multipleauthentication attempts, generate an event data structure by augmentingthe tracer data structure with timestamp data. The timestamp datarepresents a time at which the user authentication log data is observedby the computer system. The computer system also includes impossibleevent logic configured to detect an impossible event pattern within theauthentication log messages by analyzing the event data structure foreach of the multiple authentication attempts. The computer system alsoincludes filter logic configured to detect a change in behavior of auser by applying a user behavior model, representing account usagepatterns of the user, to the event data structure for each of themultiple authentication attempts.

Definitions and Other Embodiments

In another embodiment, the described methods and/or their equivalentsmay be implemented with computer executable instructions. Thus, in oneembodiment, a non-transitory computer readable/storage medium isconfigured with stored computer executable instructions of analgorithm/executable application that when executed by a machine(s)cause the machine(s) (and/or associated components) to perform themethod. Example machines include but are not limited to a processor, acomputer, a server operating in a cloud computing system, a serverconfigured in a Software as a Service (SaaS) architecture, a smartphone, and so on). In one embodiment, a computing device is implementedwith one or more executable algorithms that are configured to performany of the disclosed methods.

In one or more embodiments, the disclosed methods or their equivalentsare performed by either: computer hardware configured to perform themethod; or computer software embodied in a non-transitorycomputer-readable medium including an executable algorithm configured toperform the method.

While for purposes of simplicity of explanation, the illustratedmethodologies in the figures are shown and described as a series ofblocks of an algorithm, it is to be appreciated that the methodologiesare not limited by the order of the blocks. Some blocks can occur indifferent orders and/or concurrently with other blocks from that shownand described. Moreover, less than all the illustrated blocks may beused to implement an example methodology. Blocks may be combined orseparated into multiple actions/components. Furthermore, additionaland/or alternative methodologies can employ additional actions that arenot illustrated in blocks. The methods described herein are limited tostatutory subject matter under 35 U.S.C § 101.

The following includes definitions of selected terms employed herein.The definitions include various examples and/or forms of components thatfall within the scope of a term and that may be used for implementation.The examples are not intended to be limiting. Both singular and pluralforms of terms may be within the definitions.

References to “one embodiment”, “an embodiment”, “one example”, “anexample”, and so on, indicate that the embodiment(s) or example(s) sodescribed may include a particular feature, structure, characteristic,property, element, or limitation, but that not every embodiment orexample necessarily includes that particular feature, structure,characteristic, property, element or limitation. Furthermore, repeateduse of the phrase “in one embodiment” does not necessarily refer to thesame embodiment, though it may.

ASIC: application specific integrated circuit.

CD: compact disk.

CD-R: CD recordable.

CD-RW: CD rewriteable.

DVD: digital versatile disk and/or digital video disk.

HTTP: hypertext transfer protocol.

LAN: local area network.

RAM: random access memory.

DRAM: dynamic RAM.

SRAM: synchronous RAM.

ROM: read only memory.

PROM: programmable ROM.

EPROM: erasable PROM.

EEPROM: electrically erasable PROM.

USB: universal serial bus.

WAN: wide area network.

An “operable connection”, or a connection by which entities are“operably connected”, is one in which signals, physical communications,and/or logical communications may be sent and/or received. An operableconnection may include a physical interface, an electrical interface,and/or a data interface. An operable connection may include differingcombinations of interfaces and/or connections sufficient to allowoperable control. For example, two entities can be operably connected tocommunicate signals to each other directly or through one or moreintermediate entities (e.g., processor, operating system, logic,non-transitory computer-readable medium). An operable connection mayinclude one entity generating data and storing the data in a memory, andanother entity retrieving that data from the memory via, for example,instruction control. Logical and/or physical communication channels canbe used to create an operable connection.

A “data structure”, as used herein, is an organization of data in acomputing system that is stored in a memory, a storage device, or othercomputerized system. A data structure may be any one of, for example, adata field, a data file, a data array, a data record, a database, a datatable, a graph, a tree, a linked list, and so on. A data structure maybe formed from and contain many other data structures (e.g., a databaseincludes many data records). Other examples of data structures arepossible as well, in accordance with other embodiments.

“Computer-readable medium” or “computer storage medium”, as used herein,refers to a non-transitory medium that stores instructions and/or dataconfigured to perform one or more of the disclosed functions whenexecuted. A computer-readable medium may take forms, including, but notlimited to, non-volatile media, and volatile media. Non-volatile mediamay include, for example, optical disks, magnetic disks, and so on.Volatile media may include, for example, semiconductor memories, dynamicmemory, and so on. Common forms of a computer-readable medium mayinclude, but are not limited to, a floppy disk, a flexible disk, a harddisk, a magnetic tape, other magnetic medium, an application specificintegrated circuit (ASIC), a programmable logic device, a compact disk(CD), other optical medium, a random access memory (RAM), a read onlymemory (ROM), a memory chip or card, a memory stick, solid state storagedevice (SSD), flash drive, and other media from which a computer, aprocessor or other electronic device can function with. Each type ofmedia, if selected for implementation in one embodiment, may includestored instructions of an algorithm configured to perform one or more ofthe disclosed and/or claimed functions. Computer-readable mediadescribed herein are limited to statutory subject matter under 35 U.S.C§ 101.

“Logic”, as used herein, represents a component that is implemented withcomputer or electrical hardware, a non-transitory medium with storedinstructions of an executable application or program module, and/orcombinations of these to perform any of the functions or actions asdisclosed herein, and/or to cause a function or action from anotherlogic, method, and/or system to be performed as disclosed herein.Equivalent logic may include firmware, a microprocessor programmed withan algorithm, a discrete logic (e.g., ASIC), at least one circuit, ananalog circuit, a digital circuit, a programmed logic device, a memorydevice containing instructions of an algorithm, and so on, any of whichmay be configured to perform one or more of the disclosed functions. Inone embodiment, logic may include one or more gates, combinations ofgates, or other circuit components configured to perform one or more ofthe disclosed functions. Where multiple logics are described, it may bepossible to incorporate the multiple logics into one logic. Similarly,where a single logic is described, it may be possible to distribute thatsingle logic between multiple logics. In one embodiment, one or more ofthese logics are corresponding structure associated with performing thedisclosed and/or claimed functions. Choice of which type of logic toimplement may be based on desired system conditions or specifications.For example, if greater speed is a consideration, then hardware would beselected to implement functions. If a lower cost is a consideration,then stored instructions/executable application would be selected toimplement the functions. Logic is limited to statutory subject matterunder 35 U.S.C. § 101.

“User”, as used herein, includes but is not limited to one or morepersons, computers or other devices, or combinations of these.

While the disclosed embodiments have been illustrated and described inconsiderable detail, it is not the intention to restrict or in any waylimit the scope of the appended claims to such detail. It is, of course,not possible to describe every conceivable combination of components ormethodologies for purposes of describing the various aspects of thesubject matter. Therefore, the disclosure is not limited to the specificdetails or the illustrative examples shown and described. Thus, thisdisclosure is intended to embrace alterations, modifications, andvariations that fall within the scope of the appended claims, whichsatisfy the statutory subject matter requirements of 35 U.S.C. § 101.

To the extent that the term “includes” or “including” is employed in thedetailed description or the claims, it is intended to be inclusive in amanner similar to the term “comprising” as that term is interpreted whenemployed as a transitional word in a claim.

To the extent that the term “or” is used in the detailed description orclaims (e.g., A or B) it is intended to mean “A or B or both”. When theapplicants intend to indicate “only A or B but not both” then the phrase“only A or B but not both” will be used. Thus, use of the term “or”herein is the inclusive, and not the exclusive use.

To the extent that the phrase “one or more of, A, B, and C” is usedherein, (e.g., a data store configured to store one or more of, A, B,and C) it is intended to convey the set of possibilities A, B, C, AB,AC, BC, and/or ABC (e.g., the data store may store only A, only B, onlyC, A&B, A&C, B&C, and/or A&B&C). It is not intended to require one of A,one of B, and one of C. When the applicants intend to indicate “at leastone of A, at least one of B, and at least one of C”, then the phrasing“at least one of A, at least one of B, and at least one of C” will beused.

What is claimed is:
 1. A computer-implemented method performed by acomputing device, where the computing device includes at least aprocessor for executing instructions from a memory, the methodcomprising: for a user authentication attempt to access a securecomputer resource that results in generation of a user authenticationlog message, collecting, via at least the processor, user authenticationlog data having user attribute values; transforming, via at least theprocessor, the user authentication log data into a tracer data structurehaving the user attribute values organized in a defined format;augmenting, via at least the processor, the tracer data structure withtimestamp data to generate an event data structure, wherein thetimestamp data represents a time at which the user authentication logdata is observed by the computing device; determining, via at least theprocessor, whether the tracer data structure matches an existing tracerdata structure stored in a rules database; if the tracer data structuredoes not match the existing tracer data structure, setting a noveltyflag to establish a new tracer data structure in the rules database forgenerating a new user behavior model filter; and if the tracer datastructure matches the existing tracer data structure: (i) applying, viaat least the processor, an existing user behavior model filterrepresenting account usage patterns of the user for detecting amalicious authentication attempt to access the secure computer resourceby a malicious user, (ii) controlling issuance of an alarm message orsignal as a warning to a remote computing device in response todetecting the malicious authentication attempt, and (iii) updating, viaat least the processor, the existing user behavior model filter based,at least in part, on the event data structure.
 2. The method of claim 1,wherein transforming the user authentication log data into the tracerdata structure includes parsing the user authentication log data intothe user attribute values.
 3. The method of claim 1, wherein the definedformat of the tracer data structure includes each of the attributevalues paired with a corresponding attribute type organized in a formatthat is common to each of a plurality of user authentication attempts toaccess the secure computer resource.
 4. The method of claim 1, whereinif the tracer data structure matches the existing tracer data structure,a list of timestamps for the existing tracer data structure is updatedwith a new timestamp, wherein the list of timestamps represents aplurality of times at which the user authentication log data is observedby the computing device.
 5. The method of claim 1, wherein detecting themalicious authentication attempt further includes detecting animpossible event pattern within authentication log messages received bythe computing device from the malicious user.
 6. The method of claim 1,wherein generating the new user behavior model filter comprisestransforming the event data structure, and at least one additional eventdata structure derived from a second authentication attempt to accessthe secure computer resource, into features that describe authenticationbehavior characteristics of the user, without having to train the newuser behavior model filter using truth-labeled training data, andwithout having apriori knowledge of user authentication misuse.
 7. Themethod of claim 1, further comprising controlling user specification offilter parameters associated with at least the user behavior modelfilter via a graphical user interface or an application programinterface.
 8. The method of claim 1, wherein the user attribute valuesinclude at least one of a user name value, a client IP address value, aresource name value, a login status value, a timestamp value, anauthentication scheme value, an authentication policy value, a partnervalue, a failure code value, a retry count value, a session value, andan authentication level value.
 9. A computer system, comprising: aprocessor; a rules database device configured to store tracer datastructures having user authentication attributes organized in a definedformat; a message parsing module stored in a non-transitorycomputer-readable medium including instructions that when executed causethe processor to, for a user authentication attempt to access a securecomputer resource that results in generation of a user authenticationlog message: collect user authentication log data including userattribute values from the user authentication log message, and transformthe user authentication log data into a tracer data structure having theuser attribute values in the defined format by parsing the userauthentication log data into the user attribute values; a tracermatching module stored in the non-transitory computer-readable mediumincluding instructions that when executed cause the processor to:augment the tracer data structure with timestamp data to generate anevent data structure, wherein the timestamp data represents a time atwhich the user authentication log data is observed by the computingdevice; determine whether the tracer data structure matches an existingtracer data structure stored in a rules database; a filter module storedin the non-transitory computer-readable medium including instructionsthat when executed cause the processor to: if the tracer data structuredoes not match the existing tracer data structure, set a novelty flag toestablish a new tracer data structure in the rules database forgenerating a new user behavior model filter; and if the tracer datastructure matches the existing tracer data structure: (i) apply anexisting user behavior model filter representing account usage patternsof the user for detecting a malicious authentication attempt to accessthe secure computer resource by a malicious user, (ii) control issuanceof an alarm message or signal as a warning to a remote computing devicein response to detecting the malicious authentication attempt, and (iii)update the existing user behavior model filter based, at least in part,on the event data structure.
 10. The computer system of claim 9, furthercomprising an explain module stored in the non-transitorycomputer-readable medium including instructions that when executed causethe processor to engage at least the filter module to: determine a validexplanation for the malicious authentication attempt and generate acorresponding valid explanation message.
 11. The computer system ofclaim 9, wherein the user attribute values include at least one of auser name value, a client IP address value, a resource name value, alogin status value, a timestamp value, an authentication scheme value,an authentication policy value, a partner value, a failure code value, aretry count value, a session value, and an authentication level value.12. The computer system of claim 9, wherein the defined format of thetracer data structure includes each of the attribute values paired witha corresponding attribute type organized in a format that is common toeach of a plurality of user authentication attempts to access the securecomputer resource.
 13. The computer system of claim 9, wherein thefilter module further includes instructions that when executed cause theprocessor to detect the malicious authentication attempt based, at leastin part, on an impossible event pattern within authentication logmessages received by the computing device from the malicious user. 14.The computer system of claim 9, further comprising a visual userinterface module stored in the non-transitory computer-readable mediumincluding instructions that when executed cause the processor to providea graphical user interface that controls at least user specification offilter parameters associated with the filter module.
 15. The computersystem of claim 14, further comprising a display screen configured todisplay and facilitate user interaction with at least the graphical userinterface provided by the visual user interface module.
 16. The computersystem of claim 9, wherein the filter module includes instructions thatwhen executed cause the processor to generate the new user behaviormodel filter by transforming the event data structure, and at least oneadditional event data structure derived from a second authenticationattempt to access the secure computer resource, into features thatdescribe authentication behavior characteristics of the user, withouthaving to train the new user behavior model filter using truth-labeledtraining data, and without having apriori knowledge of userauthentication misuse.
 17. A non-transitory computer-readable mediumstoring instructions that, when executed by one or more processors of acomputing device, cause the computing device to at least: for a userauthentication attempt to access a secure computer resource that resultsin generation of a user authentication log message, collecting, via atleast the processor, user authentication log data having user attributevalues; transforming, via at least the processor, the userauthentication log data into a tracer data structure having the userattribute values organized in a defined format; augmenting, via at leastthe processor, the tracer data structure with timestamp data to generatean event data structure, wherein the timestamp data represents a time atwhich the user authentication log data is observed by the computingdevice; determining, via at least the processor, whether the tracer datastructure matches an existing tracer data structure stored in a rulesdatabase; if the tracer data structure does not match the existingtracer data structure, setting a novelty flag to establish a new tracerdata structure in the rules database for generating a new user behaviormodel filter; and if the tracer data structure matches the existingtracer data structure: (i) applying, via at least the processor, anexisting user behavior model filter representing account usage patternsof the user for detecting a malicious authentication attempt to accessthe secure computer resource by a malicious user, (ii) controllingissuance of an alarm message or signal as a warning to a remotecomputing device in response to detecting the malicious authenticationattempt, and (iii) updating, via at least the processor, the existinguser behavior model filter based, at least in part, on the event datastructure.
 18. The non-transitory computer-readable medium of claim 17,wherein the instructions further comprise instructions that, whenexecuted by the one or more processors, cause the computing device to,if the tracer data structure matches the existing tracer data structure,update a list of timestamps for the existing tracer data structure witha new timestamp, wherein the list of timestamps represents a pluralityof times when the user authentication log data was previously observedby the computing device.
 19. The non-transitory computer-readable mediumof claim 17, wherein the instructions further include instructions that,when executed by the one or more processors, causes the computing deviceto: determine a valid explanation for the malicious authenticationattempt and generate a corresponding valid explanation message.
 20. Thenon-transitory computer-readable medium of claim 17, wherein theinstructions further comprise instructions that, when executed by theone or more processors, cause the computing device to at least generatethe new user behavior model filter, at least in part, by transformingthe event data structure, and at least one additional event datastructure derived from a second authentication attempt to access thesecure computer resource, into features that describe authenticationbehavior characteristics of the user, without having to train the newuser behavior model filter using truth-labeled training data, andwithout having apriori knowledge of user authentication misuse.